A first form of the present invention relates to a framed lens making it possible to improve the sales mode of glasses. In the distribution stage, components of glasses are supplied in easy-to-assemble form or in partly assembled form to individuals to allow the latter to assemble the components into a final product.
A second form of the invention relates to interchangeable lens used for simple farsighted glasses and it also relates to a pair of glasses using the same.
Eyeglass construction changes with time, making great progress in shape, material or ornamental aspects. Basically, however, a pair of lenses are fitted in rims and connected by a bridge to form a front portion, and a lug, hinge, temple, modern, and pads are integrated to provide a final product. Further, in recent years, rimless glasses have been in fashion. On the other hand, since the advent of plastic lenses, greater importance has been put on fashionability, with people using colored lenses or glasses serving both as eyesight correcting glasses and as sunglasses. As a result, the number of people who readily use glasses is increasing and it has become no longer uncommon that a person possesses two or three pairs of glasses.
However, the so-called frame which fixes the lenses in position is not so inexpensive and right and left lenses for a pair of glasses often differ in, for example, eyesight correcting index from each other and must have their outer peripheries ground to fit them to the rim shape. In rimless glasses, drilling for fixing frame parts is required and in making glasses, it is inevitable to depend on the processor, resulting in an expensive product. Further, eyesight decreases year by year, so that each time one's eyesight becomes less than satisfactory, one has to buy a new pair of glasses.
On the other hand, with the progress of resin lenses, it has become possible to supply a lens which is high in quality, resistant to shock, light in weight, and inexpensive. In recent years, a handy camera is in wide use, using the catch phrase "Utsurun-desu" (Takes Good Pictures). This commodity is characterized in that the indispensable components of a camera, i.e. a lens, shutter, film and dark box are integrally supplied, shattering the concept that film and a camera are to be separately sold, it being understood that there may have been conceived a new idea of selling a lens-equipped film.
In the field of glasses, unlike the lens-equipped film, it is impossible to perform mass production using a single design chart. The reason is that the requirements imposed on eyeglass producers differ from user to user as to eyesight correcting lens index, astigmatism, longsightedness, shortsightedness and interpupillary distance; thus, to accommodate such varying conditions, the number of types to be prepared would be enormous.
In buying a pair of glasses, usually, the user goes to an eye doctor to get a prescription therefor. He then gives a retailer (optical shop) an order for a pair of glasses on the prescription. If the proper lenses are not in stock, they have to be procured through the distribution stage including the successive steps of the processor (laboratory), wholesaler (trading company), and lens maker. After he has obtained the desired lenses, he has to ask the processor to grind the outer edges of the lenses to fit them to the rim shape of his favorite frame. Due to passage through such stages, it takes a substantial period of time before the glasses are delivered, requiring much expense. To shorten this period, a variety of types of lenses have to be kept in stock in the distribution stage, and some of the parts in stock deteriorate with the lapse of time, and the reduced commodity value makes them unsalable. At any rate, when a glasses user buys a pair of glasses, various processing steps are required, making it impossible to obtain it readily or inexpensively.
Further, glasses have right and left lenses in a pair, but usually, the right and left lenses differ in prescription, a factor which prolongs the time of delivery. Therefore, to shorten, if any, the time of delivery, there are found many patent applications relating to removable frames convenient for changing lenses, and among these applications there is one proposing a pair of disposable glasses, as disclosed in Japanese Utility Model Kokai Sho 63-80526. Further, it has become common practice for optical shops to grind lenses to fit them to rims.
The first form of this invention is based on the principle that, in order to provide a glasses lens which is light in weight, resistant to shock and inexpensive, a glasses frame (hereinafter referred to as frame) and lenses are integrated.
The problem to be solved is to provide members for glasses which make it possible for a glasses user to select proper lenses for his eye prescription and a necessary minimum number of members required for mounting the lenses, so that he is allowed to complete a pair of glasses by himself.
As for glasses using eyesight correcting lenses, first, the user selects his favorite glasses frame and the processor grinds the peripheries of the lenses matching the user's right and left eye prescriptions and then fits the lenses in the frame and the optical distributor presents the product as a pair of glasses. This is a common method. Usually, the lens producer produces circular lenses of about 70 mm in diameter and supplies them to the distributor. In the distributor's shop, the lens contour is ground according to the shape of the frame selected by the user.
The lens producer in the aforesaid sales mode is obliged to present lenses including the material to be later removed by grinding, and the cost of said surplus material is, after all, borne by the user. When the user desires a pair of fashionable glasses, he can afford to bear such cost, but in the case of glasses which are practical and which should not be so inconvenient to the user, e.g., a pair of farsighted glasses, it is desired that the glasses be as inexpensive as possible.
As considered from the lens producer's circumstances, it is desired that lenses be produced in a practical shape with the intention of excluding the wasteful material as much as possible. On the other hand, in the case of a plastic lens produced by cast-molding, molds and gaskets for producing lenses of practical shape have to be prepared. Particularly, molds are expensive. And such molds have to coincide with the contour of a lens and two molds are required to constitute a cell (shown in FIG. 11), and if the contour is changed, the same molds cannot be used. This problem is also the case with gaskets, and the same molds for an injection molding machine for producing gaskets cannot be used in such case.
For the above reason, it might be thought to be most convenient if lenses could be made by injection molding. However, since there are two lens contour shapes for the right and left eyes, two types of molds are required. Even in the case of a lens whose eyesight correcting index alone is considered to be most important, such as farsighted glasses, there are as many as five index values 1.0, 1.5, 2.0, 2.5, and 3.0, and to prepare lenses of these index values, ten types of molds are necessary. Molds for lenses must have their surfaces accurately ground and are inevitably expensive, adding to the cost of lenses.
The problem to be solved in the second form of the invention is to provide a glasses lens and glasses using the same, which make it possible to simplify the lens making process, and decrease the number of types of molds and the amount of stock.